Integrated circuit chips (IC chips) or semiconductor die are typically encapsulated in a package to protect the circuitry formed on the semiconductor die from external elements. An IC chip includes bond pads formed thereon. Bond wires, or other electrical connection means, are used to electrically connect the bond pads to corresponding pins or leads of the integrated circuit package. The bond pads can be power pads for power supply voltages connections and input/output (I/O) pads for connecting to input and output signals of the integrated circuit. An I/O circuit is a circuit coupled to an I/O pad of a chip and configured to communicate input and/or output signals with other chips in the integrated circuit system.
A glitch is an undesired transition state that occurs before a signal settles to its intended value. Glitching poses a critical issue for an I/O circuit, e.g. during power ramp-up of the circuit. A key factor impacting the glitch issue in an I/O circuit is the signal sequence of a data signal and an output enable signal in the I/O circuit. In a conventional method, the signal sequence is controlled by system level signals, which is not suitable for high-speed circuit operations. In another conventional method, a power-on-control (POC) mechanism is required to be added externally to control the I/O circuit in tristate and avoid crowbar-currents during power ramp up. For this external POC method, customers of the integrated circuit have to modify their system design to control POC behavior by themselves, which is a huge effort for the customers. As such, existing I/O circuits are not entirely satisfactory in terms of glitch prevention.